I'm getting the sense that you're trying to use this thread as your soap-box against corporate interest.
Even if gay marriage had a threat to business (which it doesn't and has no potential to be such), the overall cultural shift in America toward supporting gay rights would override any pre-existing interest (or in your fictional terms, big business) against gay rights.
Such was the case with Title 2 of the Civil Rights Act of 1964. While some businesses opposed having to provide their services equally, Title 2 was still passed.
Further, opposing gay marriage has hurt businesses (in reality mind you). Look at the Chick-fil-A controversy. Because of their support for homophobic agendas, they lost a lucrative partnership with the Jim Henson Company, had two large universities disallow Chick-fil-A from providing their services until they changed their policies and had three major cities threaten to ban Chick-fil-A from opening franchises within their city limits (which was stupid BTW but still served a dose of negative publicity).
With regard to your original post in this thread, it is fallacious to equate a denial of service (eg segregated restaurants, non-protected gay marriage) with restricted use of intellectual property as a service is seen as something public while an IP is seen as something private. Anyone can use a service, only a few can use an IP. That's why an IP is called property.